Research and development of a semiconductor laser device having a 400 nm wavelength for next generation DVDs is proceeding.
On the other hand, a semiconductor laser device having 650 nm band and 780 nm band wavelengths is used for recording and reading current generation DVDs and CDs. For purposes herein, a semiconductor laser device that generates two or more bands of wavelengths is referred to as a multiple wavelengths semiconductor laser device.
It is difficult to form a multiple semiconductor laser device, which is capable of emitting 400 nm, 650 nm, and 780 nm, on single a semiconductor substrate.